Lecture 2 Flashcards
What is astrobiology about?
Understanding life on earth and its evolution.
How can we understand the evolution of the solar system and earth itself?
How can we predict the future evolution of the solar system and life in it?
Are we alone in the universe?
Why is it less likely that we find silicon based life?
There are less number of possibilities than of carbon based (organic) chemistry.
What is the problem by assuming random possibilities of organic chemistry?
If we assume a random mix of simple building blocks (Amino acids and up), it would take about 10^120 years to build life.
Why do we know that life has to follow certain laws and pathways or we are alone?
Because it would take about 10^120 years to build life because of random possibilities of organic chemistry.
What could have been a possible pathway for life 4Gyr ago?
Formation of amino acids -> Nitrogeneous bases -> monosaccharides -> Fatty acids -> nucleic acids -> proteins -> carbohydrates and lipids -> cell membrane
(ANMFNPC(L)C)
(AKMFNPCC)Swedish
Why does life as we know require a solvent?
Free transportation of building blocks, Transportation of nourishment, transportation of waste.
Name some reasons why water is unique.
Bindings between H and O are strongly polarized.
Angles between H and O form a dipole.
Bonds between H20 molecules give water high melting points, boiling points and surface tension.
Water can be ionized into behaving either as a base or acid.
Which type of cell is DNA found in?
Eukaryotic cell
What are the domains of life?
Prokaryota (Bacteria and archaea) Eukaryota (Fungi, plantae and animalia(Protista))
What are the roles of RNA?
Coding and decoding, regulation of genes, expression of genes.
Big differences (structurally) between RNA and DNA?
RNA is single strand, DNA is double. Uracil in RNA replaces Thymine in DNA.
What is the bases (A-T, G-C) mounted on?
A phosphate group base.
How much larger are eukaryotic cells than prokaryotes?
about 10 000.
What is the probable origin mitochondria?
They are probably decended from bacteria that survived endocytosis by another cell and became incorporated in the cytoplasm 1.7-2 Gyrs ago.
How many chromosomes does organisms without a cell nucleus have?
One ring formed, free floating.
How many amino acids form all the proteins?
20 of them
How many amino acids does a protein consist of?
more than a 1000.
How much of the dry mass of a cell constitute of proteins?
about half.
What are some functions that proteins perform?
They build up and hold the cell together.
Catalyze metabolic reactions (Enzymes)
Replicate DNA
Responding to stimuli
Transporting molecules
Receptors
What are carbohydrates and what are they good for?
monosacharides and polysacharides. DNA and RNA contain carbohydrates and photosynthesis uses it to create carbohydrates with oxygen as waste, the carbohydrates can then be metabolized.
What are lipids?
Fats, phospholipids, glycolipids and steroids. They are used by cells as energy storage and vitamin carriers. Phospholipids are the main components of cell membranes.
What is adenotrifosfate and where can it be found?
ATP acquires, stores and tranports energy in chemical form. Universal energy currency for all life on earth. Located in the mitochondria.
What is Schrödinger’s paradox?
In a world governed by the 2nd law of thermodynamics isolated systems are expected to tend to a state of maximum disorder.
Life approaches and maintains a highly ordered state – does this violate the 2nd Law?
Mention 3 possibilities about how life could have emerged on earth.
Gases in the atmosphere with energy in the form of lightning or impacts of heavenly bodies could form amino acids which were deposited in a cold sea (which would allow for a long life time)
Iron-sulphur rich environment along the borders of continental plates (hot sites with a reducing environment)
External arrival (meteors, comets)
What is LUCA?
Last universal common ancestor. It originated about >3.5 Gyr ago. It had to have all the basic complexities of life today (DNA and RNA).
Where does metals (m > m_H) originate from?
Stellar wind of red giants and in supernovae.
What is the “Nice model”?
A scenario for the dynamical evolution of the early solar system.
What is a likely way that the moon formed?
By earth getting impacted by a mars-sized body. Similar events have been observed. This happened nearly 4.57 billion years ago, not long after earth was formed.
